In manufacturing an acrylic fiber using a wet spinning technique, after a spinning solution has been discharged from a spinning nozzle and coagulated in a coagulation bath, if coagulated filaments (fibers) that are in a wet state due to an organic solvent in the spinning solution are immediately dried as they are, the fibers adhere to one another. To address this issue, a method is generally employed in which the organic solvent in the fibers is removed beforehand through a washing step in a water tank (water bath) prior to drying. For example, Patent Document 1 discloses that prior to drying a wet-spun acrylic fiber, an organic solvent is removed by washing the acrylic fiber in a washing bath at a high temperature.